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Discussion Starter · #1 ·
All,

I have a 93 toyota, 22RE 4 cyl, with about 198,000 miles. I had the head gasket replaced last year, at about 170,000 miles. It has a terrible misfire at idle, and also when I rev the engine. I checked the codes and the computer is spitting out CEL code 12. (RPM SIGNAL-NO SIGNAL TO ECU FROM DISTRIBUTO) or ( KNOCK SENSOR SIGNAL--OPEN OR SHORT IN KNOCK SENSOR SIGNAL)

Here is what I replaced so far: cap, rotor, plugs, wires (all toyota OEM) I did a compression check, and it is measuring 182 psi across all cylinders, give or take a few psi. I cleaned out the throttle body, and man it has smooth gas pedal response.

I took it to a smog test only center over the weekend and here is what the guy measured:

HC (95-Max) (19-Ave) (126-Meas) at 15 MPH (2689 RPM)
HC (60-Max) (12-Ave) (80 - Meas) at 25 MPH (2572 RPM)

CO (0.75-Max) (0.06-Ave) (0.58-Meas) at 15 MPH (2689 RPM)
CO (0.90-Max) (0.05-Ave) (0.52-Meas) at 25 MPH (2572 RPM)

NO (552 PPM-Max) (136 PPM-Ave) (195-Meas) at 15 MPH (2689 RPM)
NO (805 PPM-Max) (124 PPM-Ave) (139-Meas) at 25 MPH (2572 RPM)

The smog guy also checked the timing, and said it was within specs, he said it was at 5 deg, BTC, but that his timing light shows it off by about 3 degrees. He said the California limit is 5 degrees in both directions.

I just don't get it, the truck runs smooth, gets pretty good gas mileage. But at a stop light, the truck stick shift looks moves back and forth almost 2-3 inches in both directions. The motor is also shacking back and fourth.

I also tested the TPS, and it is testing fine.

I don't want to keep on throwing more money just to get it smogged. I'm already out $47 dollars for the test, without certificate.

Any suggestions, I have about 3 days to get this thing smogged, or else I need to get it in non-op with a red-sticker til I find a solution.

The dealer wants about $100 dollars just to stick in on a dignostic, but I don't want to pay $100 dollars to hear them say you have a missing cylinder, I know this!!

Please reply,

reezytercel
 

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If you check the ENGINE - MFI SYSTEM - DIAGNOSTICS section of the factory manual (fsm), code 12 means the ecu isn't receiving the NE signal, which is the crankshaft position signal that is supposed to be sent by the distributor to the ecu. It is generated by the signal rotor (4-lobed metal starwheel under the rotor in the distributor), moving past the signal generating coil. There's a picture of them in the IGNITION - DISTRIBUTOR section of the fsm, and specs and instructions for testing them in the IGNITION - ON VEHICLE INSPECTION section. (If you don't have an fsm, google 1993 toyota pickup service manual.

First I would check that the connector on the side of the distributor is clean and secure. That connector has to be clean because even a little corrosion will prevent the very weak NE signal from making it to the ecu. Also check the connections at the coil and igniter, and make sure the ground of the igniter/coil is good - maybe pull them off and clean the corrosion off where they mount.

Unless you find something obvious wrong with a connector, you should check the clearance between the signal rotor and the signal coil projection with a feeler gauge (check the clearance of all four lobes), and also check the resistance of the signal generating coil with an ohmmeter as described in the ON VEHICLE INSPECTION section.

While you've got the ohmmeter out, may as well check the resistance of the primary and secondary coil circuits in your coil - instructions in the IGNITION - ON VEHICLE INSPECTION section.

If it turns out the problem is the signal generating coil resistance, you can replace that part. rockauto.com carries it from 3 suppliers, none of which I'm crazy about, but I guess since Airtex is sub-par and on general principle I won't put anything from AC Delco in my Toyota, that I would recommend the Standard Motor Products part. But without much enthusiasm:

http://www.rockauto.com/catalog/x,carcode,1277984,parttype,7176,partGroup,25

You also might try 1sttoyotaparts.com, or even a junkyard, for that matter. Getting a new or remanufactured distributor is another option, but make sure it comes with the pickup coil.
 

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Discussion Starter · #3 ·
Update -- More Ohm Meter measurements

sb5walker,

thanks for your post. It is 57% here in Southern California, so my ambient temperature is 57% which is considered Cold during these measurements.

Here is what I measured:

Primary Coil resistance (cold). I measured 0.5 ohms, (specs 0.36-0.55ohms)
Secondary Coil resistance (cold). I measured 12.1K ohms, (specs 9.0-15.4Kohms)

Distributor Air Gaps (specs 0.2-0.4mm or 0.008-0.015in.)
Rotor 1 air gap = 0.010in
Rotor 2 air gap = 0.011in
Rotor 3 air gap = 0.013in
Rotor 4 air gap = 0.013in
The 0.008in was way too loose on all rotors, and the 0.015in was way too tight on all rotors. I would estimate that it is with in specs. This does not account for any changes due to temperature.

Lastly, I measured 229 ohms on the signal generator (pickup-coil) resistance.

Any other thoughts on this misfire?

Could it be related to my injectors? I know I'm getting fuel, because my HC levels are high, but just not getting spark or proper combustion. I'm stumbled on this one. Any suggestions?

Thanks,

reezytercel
 

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Discussion Starter · #4 ·
timing light information

All,
just to verify idle and timing, I verified the timing again with a timing light.
With the diagnostic connector shorted out, the timing was at 5 degrees. the funny thing was that the mark kept on moving back and forth, when I was testing under cylinder 1, I moved the induction pickup of the timing light to cylinder number 4, which is 180 degrees off, still at the 5 degree mark, but man the mark did not dance as much.

Could this be an indication of something else wrong?

I checked the idle, and it was at 750 with the diagnostic connector short removed.

Funny thing, is I reved the motor, got the RPMs up to around 2500, 2700, and then let the idle drop. it sometimes will not go down to 750. It takes a few revs and releases of the gas pedal to get it back down to 750. Not sure what is going on with this.

Lastly, I can even turn the idle screw down, it bottoms out, and my idle is stilll at 750? Huh?

Still getting CEL code 12.

Idle is still rough at idle, smooth at higher revs, but I can hear and feel a slight misfire. The misfire is very apparent at idle, and slightly apparent at high RPM, but it is still there.

I'm that close to sending this to Toyota, so they can run a diagnostic. Has anyone done that before, is the report going to show exactly what is wrong, or is it a general, "misfire on cylinder 4" as an example. I already know I have a misfire, so I don't want to pay for something I already know. In other words how extensive is the Toyota dealership diagnostic report?

any other suggestions?

Thanks,
reezytercel
 

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1994 XtraCab 4x4 P/U
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If the idle screw is at the bottom & you still have high idle, you have a vacuum leak, or the throttle body butterfly is worn out or sticking open.
 

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Your tests show the signal generating coil should be making an NE signal okay, but your code 12 says the signal is not making it back to the ECU. That is a problem that you'll need to track down. I have the 3vze, so my distributor is connected differently. I know the 22re distributor connects to the igniter, and the igniter passes the NE signal on to the ecu. So either a bad connection between distrib & igniter, bad igniter, or bad connection between igniter & ecu.

Check all connections, clean them, remove coil & igniter and clean the igniter ground. Sometimes a pin is pushed back in a connector so it doesn't make contact - so check all pins in the connectors.

Your timing sounds fine.

Your engine should stall or very nearly stall when the adjusting screw is all the way down. Could be vacuum leak, could be someone adjusted the throttle stop screw in a misguided attempt to set idle :hammer: could be the cold air bypass is stuck open, or the a/c idle up valve is stuck open (unlikely).

For the throttle not closing problem, check the fsm instructions for checking the throttle opener.

Don't even think of sending it to a dealer. What a laugh! I had a rough idle problem right when I bough my truck, and I took it to two different dealerships with the express instruction to diagnose the idle problem. Both dealers did unnecessary work, charged me, and didn't do jack shit to fix the idle problem. Finally, after failing smog, with the help over the phone from a reputable independent shop, I checked the tps and IDL & E2 did not have continuity at idle - which is the signal to the ecu that the throttle is at idle. Replaced the tps and it purred at idle, and has ever since. Wouldn't you think the dealers would have checked the tps idle signal when the complaint was rough idle??? :hammer::hammer::hammer: Save your money - you are more likely to find and fix the problem than they are - keep at it.
 

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Discussion Starter · #7 ·
93 Toyota Pickup -- Misfire need help, trying to smog, MORE TROUBLESHOOTING NEEDED.

All,

would the fact that I took the plug wires off each spark plug while the truck was running, turn on the CEL code 12?

I pulled one at a time to see which cylinder was giving me problems, and all cylinders, except for cylinder number 4 stalled the truck. So I'm guessing that cylinder #4 is my problem cylinder. I may have turned on this CEL code myself. (correct me if I'm wrong)

What I'm thinking is that I created this CEL code myself, and my real problem is related to vacuum.

I checked the compression and it is solid, but I'm thinking that I need to adjust the valves, especially on cylinder number 4.

I'm going in circles, at this point.

I'm going to reset the codes by removing the battery cable.

I'll run the truck around for a few miles, and then see if the code comes back. Any sort of length that I need to drive the truck to turn the codes back on?

Thanks all,

reezytercel
 

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All,

would the fact that I took the plug wires off each spark plug while the truck was running, turn on the CEL code 12?
No, probably not. Totally different circuit.

I pulled one at a time to see which cylinder was giving me problems, and all cylinders, except for cylinder number 4 stalled the truck. So I'm guessing that cylinder #4 is my problem cylinder. I may have turned on this CEL code myself. (correct me if I'm wrong)

What I'm thinking is that I created this CEL code myself, and my real problem is related to vacuum.

I checked the compression and it is solid, but I'm thinking that I need to adjust the valves, especially on cylinder number 4.

I'm going in circles, at this point.
Did you check and clean up the connectors at the distributor, igniter/coil and clean up the igniter ground?

I'm going to reset the codes by removing the battery cable.

I'll run the truck around for a few miles, and then see if the code comes back. Any sort of length that I need to drive the truck to turn the codes back on?
It's the kind of code that comes at startup. So if the problem still exists, a few starts may do it, or it may be intermittent, in which case, no telling when it might crop up again.
 

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Discussion Starter · #9 · (Edited)
93 Toyota Pickup -- misfire need help, trying to smog -- UPDATE

sb5walker,

I diagnosed my truck this evening, and I was thinking more on the lines of a vacuum leak, so I started moving hoses around, checking for any noise, sure enough, I could hear a slight suction sound, it was coming from the back of engine compartment, near the EGR valve.

So I sprayed some carb cleaner, and sure enough the idle smoothed out. I have a large vacuum leak at the EGR valve. I tested it a few times, reved the engine, sprayed near the bottom of the EGR valve, and the top of the EGR valve, where it connects to the Head. the idle goes up when sprayed!!!

Since this is part of the intake manifold gasket as well, I will need to replace my intake manifold gasket, which should stop this leak as well.

As for the truck, man after cleaning out the throttle body, new wires, plugs, cap and rotor, the motor feels strong and tight, except for this damn leak.

I plan to work on it in a few weeks, right now have other projects to work on. Maybe able to slip it in on saturday morning. While I'm at it I will replace any worn vacuum hoses.

This should correct my idle as well as my misfire, I hope.

Keep you posted, thanks for all your help. Man it is the simple things that matter. You are right, If I took this to the stealership, they would have charged me a grip, and replaced lots of other parts that are not needed.

Also, the CEL code did not come back, after about 15 mins idling. I think I caused the CEL to register, when I was messing with the plug wires. Anyway, I will work on the intake gasket, and then check for the CEL code after...

reezytercel
 
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